The firing pin is no simple lathe operation due to the positive-retracting design and the stock break is the worst-case scenario. That being, someone had tried to repair it themselves using some sort of polyurethane glue. I've said it a thousand times, I don't care how shit-hot you were in high-school wood shop, a gun stock is not a birdhouse. The only thing a half-arsed repair does it make it twice as difficult to repair it properly when the previous repair fails. Given the gun's overall condition, the goal is to make the stock look not only unrepaired but also unrefinished since a beautifully refinished stock would look quite suspicious and incorrect. On to the photos.
The broken stock, with quite a few sizeable missing pieces
While the stock was soaking in lacquer thinner to remove the old glue, I made the firing pin. The broken right side pin and the unbroken left pin. Most "gunsmiths" would braze or, worse yet, weld a piece of round stock to replace the broken portion and call it done. That would not be in keeping with the overall quality of the gun so a new part was made in O1.
The blank milled from bar stock, from here on, it's all hand work.
The new firing pin, heat treated and ready to install (after polishing the nose)
The lug on the lower arm engages a cam slot on the inside of the hammer, causing the firing pin to retract when the hammer is cocked.
Now, on to the stock...
After allowing the parts to dry completely, the mating surfaces are "adjusted" so that the outer edges mate as perfectly as possible then the whole works is epoxied and clamped in place in a fixture to make certain that nothing moves until the epoxy cures.
With the major parts reassembled, I had to make some parts to stand in for those missing.
It would be foolhardy to depend upon the epoxy joints alone to hold the stock together so a slot is machined in the hand to almost full depth and long enough to bridge the entire repaired area. A piece of solid walnut is fitted in the slot and epoxied. After the epoxy cures the triggerplate and guard are re-inletted.
After staining and oiling, the gun is reassembled and the job is finished.